Automatic telephone system



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i H. M. FRIENDLY AUTOMATIC TELEPHONE SYSTEM Filed May s. 1921 15 sheets-sheet 5 May 1o. 1927. 1,628,359

H. M. FRIENDLY AUTOMATI C TELEPHONE SYSTEM Filed May s. 1921 15 sheets-sheet 6 mf- H13-FEET Mfmand lg May 10, 1927.

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H. M. FRIENDLY AUTOMATIC TELEPHONE SYSTEM Filed May 3. 1921 l5 Sheets-Sheet l2 fi L5;

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H. M. FRIENDLY AUTOMATIC TELEPHONE SYSTEM Filed May 3. 1921 15 Sheets-Sheet 14 H'rllf'mendly Wfm flu-ys:

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Patented May l0, 1927.

UNITED STATES PATENT oFFiCE.

HERBERT FRIENDLY, OF PORTLAND, OREGON.

AUTOMATIC TELEPHONE SYSTEM.

Aapplication led lMay 3, 1921. Serial No. 466,433.

automaticexchanges. l

One of the principal objectsot' the inven. tion` is t04 Pl'hovide a private vautomatic exechangel system ivhic'h will operate Without change in conjunction with either afman'ual or automatic'v main exchange. Thisis important view "ofthe lfactv that a great many manual telephone systems are novvi be.- ing replaced by automatic systems and in all probability'all manual systems ivill be so replaced.. It will be seen therefore that a great advantageisobtained if the circuits of the private automatic exchanges are so designedthat when themain exchange service is changed from manna"L to automatic the private automatic exchange equipmentcan still be used without having tov revise the circuits in anyparticular.

In carrying fout the general object above set forth a large number of new features have been incorporated in the system,'the principal ones of which will be briefly pointed out below:

, ln private automatic exchange systems it is desirable when a subscriber in the main exchange calls a subscriber in the private automatic exchange to provide means Whereby the connection may bepassed or transferred to another party; and that this transferring operation may be performed by either the calling subscriber (if he is located in an automatic exchange) or the called subscriber. It will be apparent that Where the private automatic exchange is large say of from 5IN) to 1000 or more subscribers the cost of furnishing this transfer call servicc to all the subscribers may become prohibitive. According to the present invention somewhat less than 100 subscribers in a large private automatic exchange are given this class of service. In the city directory are listed only the names of these subscribcrs. Non'. when one of these is called by a main exchange subscriber if it should be Systems of y this type Y are well known under theA name'ofvprivate found that another party in the branch exchange is desired, the called subscriber may, by operating his calling device, extend the connection to the party desired7 if it is one of the selected group of subscribers( However, should it be one of the other subscribers in the private automatic exchange,

the called subscriber is able to signalwan attendant operator. 'lhevattendant operator has a multiple of Aall local lines b'eforeher and after ascertaining the nun'iber of the:

desired local station she may-extend the connection to that line manually. lVhen the calling subscriber in the main exchangev does Ilot find the number of the particular subscriber inthe private auton'iatic exchange he desires listed in the directory, he may call the attendant operator who, after ascertaining his Wants Wil extend the connection to the desired local subscriber. In this manner ,While all the branch exchange subscribers may be reached from'the main exchange the expensive and complicated automatic passing call apparatus is supplied only1 for a small number of subscribers.

A further feature of the invention relates to an improved night service arrangement whereby a plug ending trunk extending from a main exchange to a branch exchange connected to a local line. lVhen the trunk is seized from the main exchange ringing cur rent is automatically projected out on the preconnected ocal line until an answer is obtained. lhen this occurs the subscriber called may pass or trans-ter the call to another party in the branch exchange.

Another object provides means so that when the trunk line is not in use the preconnected branch exchange substation may call and be called and also whenever it becomes busv a busy potential is applied to the trunk line in the main exchange. y

Still another feature provides new and improved means for preventing any calls made on an incoming trunk line to the branch ex 'change from being completed without thc intervention of the attendant operator.

Further objects reate lo means for restricting the calling of certain lines cr certain groups of lines to main exchange suhscribersvx though at the same time they are still accessible to the attendant. This restriction may be optionaliy controlled from certain of the local substations.

Further features relate to the provision of a special busy release circuit of the alltomatic switches used in transferring the call to the provision of new supervisory circuits whereby the attendant and main exchange operators (provided the main exchange is operating manually) are notified of the. vari ous operations; and to prov-ide special cir'- cuits for signalling the operator in the branch exchange.

There are a number of other features not now specifically mentioned which together with the foregoing will be described hereinafter, with reference to the .accompanying drawings.

Referring now to the drawings. in Fig. 1 is shown a schematic trunlting diagram ot an automatic exchange system of the above character.

F-igsj2 and 2^ show in general the equipment in both the manual and automatic main exch'ange,' the l'ampar'atiis' in manual exchange 'being shown in' 'the lower portion of the sheet and cnsistingllo'f a cord circuit O and the equipment associated! with the trunk line which terminates in the jack J. The automatic apparatus shown in the upper portion of the sheetand consists of a selector repeater indicated diagrammatically atE, the line switch C, of the well known j plunger. type whichis associated with the 'trunk line comprising conductors 51 and 52 extending to the branchexchange. The line switchv C is one of a group of line switches all adapted to be controlled in the well known manner by a master switch (not shown) the function of which is to maintain the plungers of all idle line switches opposite an idle trunk line. The line switch C and similar line switches have access to first selectors one of which is indicated at D. The key K is adapted to transfer the trunk line extending to the priva-te automatic exchange from manual to automatic operation, when the manual exchange is cut over= to automatic use.

Figs. 3 and 4 show the trunk line comprising conductors 51 and 52 extending into the private automatic exchange and also the trunk equipment associated with this trunk line in the attendants cabinet. The jack J3 is a terminal of the trunk line accessible to the attendant operator and is used by the attendant in extending the local subscribers lines to the main exchange. The plug P2 is used for night service and also for transferring a connection from the trunk line to a local substation.

In Figs. 5, 6, 7 and S are shown two dual connector switches in which the incoming trunk line terminates., These connectors are of the usual type used for passing calls each having access to local subscribers lines and trunk lines extending to an isolated private branch exchange. The bank contacts 615-618 being the terminal of such a trunk line in the main connector H and having the multiple' bank 'contacts 390-393, inclusive, accessible to the auxiliary connector H. The bank contacts 620-623, inclusive, in the main connectorH are associated with the line of the substation A5 while the bank contacts 6254-628, inclusive, are associated with the line of the substation A4. These bank contacts are ofcourse multipled in the usual manner Yin the auxiliary dual connector switch H' and all other local connector switches which have access to the lines ot these substations.

T hesubstations A* and A5, Fig. 9 and also thel trunk v line extending to the` private braneh'lexchange, Fig. 10, have individual line switches of the plunger type associated therewith. `Theselinc switches'are adapted to be controlled by'la" master switch (not shown), in the well known manner. The jackshJGLJand ,J5 enable the attendant'- opera'itorfto'connect manually with the substations A* and Aand the trunk line extendingI tothe private branch exchange, respee tively.,

"Theequipment in the isolated branch exchange is shown in Fig. l0 and consists of a cord circuit O and a manual substation A7 the latter having the usual line equip ment associated with it. The trunk lines accessible tothe -line-,switches C4, C5 and C1 terminate in the local first selector switches one ofwhich is shown at D2, Fig. l1. This selector is of the usuatStrowger type haw ing access to trunk lines leading to the attendant operator from the first level while from the second level the truuk lines lead to local connector selector repeaters one of which is shown at H. From the third anvl other levels ot the first selectors the trunk lines lead to local connector switches of the usual type. These switches have access to local subscribers`r lines only. and conscquently their operation is similar to that of the .connector switch ll`' on the third to the eighth levels, inclusive, where it also has access to local subscribers lines. The con nector H2 is of the well known Strowger vertical and rotary type and has the usual setof bank contacts arranged in ten groups or levels. From the third to the eighth level this switch functions as an ordinary connector switch and has access to local subscribers` lines. On the first and second levels the connector has access to trunk lines leading to the information and complaint operators in the private automatic exchange. On the ninth level the connector selector repeaters have access to trunk lines leading to the private branch exchange, while on the tenth level these switches have lUtl access to trunk lines leading to the main exi-l T he` substation A8 which is'aceessible-'tothe connector selector repeater H2' chan' f.

has-tbe individualv lir-rcsnitch yC8 Aand the En Fig. l1a s'shown a mechanical interlocking device' which 'is adapted tof-be used onfcertainrelay'sj in thezlocail connector selec# tor' repeaters such-as Hf 10i Fig. 11' showsafdetail of the-shaft of-Fig.

11 with relation to the cam-springs- 9094-912 and 905-9081;" Fig. 12:' shows lthe cordvcircuit usedA by vthe' "'Figx'la shcwsthemamief 'which certain sheet'sfof dniw'ingfs vshould beplaced in orderV cuits" of" the"coinplaint3 information, andl attendan'tf operators, respectively, "whereby these operators Inayb'e signalled by Ithe local private automatic'ex'change subscribers.

call received/froth "axtirnlt' tothe jaclt'J: osi'm'ilr jlicksf Fig. 18 shonjs'a modification ofthe cord aan @Kerala straffelbyfrwfiyzf-ffhe U circuit O used by the r'r'ainv exchange oper-I atioi" `whereby the:`s`i1pervisionv is controlled relate to the. iii'qht service circuits'and Avvill bel discussed moie'in c letail.hereinaftern A L Fig. 21 shovelsy a' vcord circuit which is adapted' to' be used by'the .attendant operator inthe private automatic exchange .nhe'n the main exchange.isfoperatingmanually y The mannerin which aconn'ction local to the main [exchange is completed will non i be described generally with reference to Fig'.

1. AFor this purpose it will be assumed that. the subscriber at substation A desiresto callI the subscriber at substation A. Undervthese conditions the callingr subscriber willre'movey his receiver and operate his callingr device for the digits of the number assigned to the subscriber at substation A'. B v these op-V erations the line switch individual tothe calling subscribeids line operates to auto-V matically select an. idle trunk leading to a first selector such as l). This lirst selector D is then operated in response to the first digit of the desired subscribe1"sl number to the proper level and thenv automatically rotates to select anidle trunk terminating in a-.second selector such as D. The selector D is operated opposite the level correspondingr to the'second digit called by the calling)r subscriber and in thc saine manner as the lirst selector l) operates to'select an idle connector Vswitolnf whicha'has yaccess to the linefofthe subscriber at sobstations'Aandz. rVnhichfit will be assumed is the connector,

indicateddiagrammatieally at H. In'r'esponsento. the lasttwo digits. ot' the called subscribers number lthe connector H4 1S- operated -ifnthe vusual manne-r into engage-I n'ient avith the-desired subscribers line. Afteufthe-conversation `is terminated the connec-tron:.saeleased rn' the usual. automatic manner by the fcallingI subsc ri ber replacing.

lrsllreceive r 1 upon. the switchhoolc -Will now be assumed that `the subscriber at'substationfAhdesires toestablish a con# neeti'on'witth the subscriberat substation A"A irr'they private automatic exchangeu lVhen the receiverfisremoved thefrota ry -hne switch individual to't'hel'ine ofthe substation proper level land-'rotates to automatie-ally` select an. idle" selector frepeater f such as thex `switch El Enr response to' thel secondf i digit..- dial'lcd y the calling: subscriber the selector repeater f operated! opposite the level in' which the 'trunk li nesare terminated leading' to-'ftlfte-fprivate automatic exchanfcre.` vlnthe usualf'nanner the sWit'chfE then Operatesto select an iidle'one of theseftrunl; lines, 'which we' will' assume,t isthe' trunk linev shown ex te'niliing through th'e''attendan'tls'cabinet N atthe'private fautomatic exchange and ter mina/tinj in dual Connectors 1H and In response to theI last t'wo digitsof the numberI oftheI substation Attthe.- main connector ll is operated :into engagement with'thefbank contacts associated with tlieline of the sub scriber. i If the calledsubscribersline hapA pens to be bnsymt thi-s1 time the main con neet/or' H'Wiil'l bei autornatically'Y released and the calling! subscriber given they busy signal..

There is now open to the calling subscriber two courses, one ot' which is to replace 'his receiver on the'switclfihook thereby releasing` the operated switches in the Well known man'neiror lrernay b v-operating his callingr device for the Y'last two digits of another branch exchange subscribes number operate the auxiliary connector H into 'connection with this other subscribers line. lf it shouldy be' iiound lafter ,conversing with the called branch exchange subscriber that another party in the branch' exchange is desired either'the callingr or the called subscriber may by operating his calling device causo the main connector H to be loperated into connection with the desired suhscribens line. ln the former case the' first digit diallcd by the calling subscriber serves to release tln` auxiliary connector ll'. ln the latter case thc conncfor ll is not automatically released. Should this subscribens line happen l: LU

toflbe'busyi the -mainconneetorffH lWil-ll beA automatically: released andfthe first,- called subscriber may re'operate itif he so desires.t Atterconnection ifsniade .with the desiredV "second branch exchange subscribers line ythe firstcalled party. by replacing: his vreceiver upon thefswitchhook' will ielease lthe auxiliary connector switch H. vElow-ever,ifhe holds Ithe line untilth'e fsecondi calledu'subsc riber-lanswers a: three :party-iconferenoe may be fheldd AtI the'ft'eriniimtionf= of. ,t'his. conference either called' party fby: operating hsciallingrr device-s enabled to'release tlieicotineotion t-.Ttl'ieiotlier branch ,exchangefsub-,- scr'ihers,line-.-v Should `tlie-tirst called subscriber replace Zhis i'eceiverjnponthe switchhook :he willrelease Eth'e ,auxiliary connector H. and in, Ylike i manncrf the: second' called subscriber :upon hanginglup would release theinainconnector 5 --ltfmayulnowt happeni'that ianother si 1b scriber-y yin the private :automatic exchange is tlesiredvwhose'line noti/accessible to; the dual/connector switches/Hiand Under; thesel condiitions,f,it: will; .be necessary fto= sig,- nalthefattendantfmperator. and have her completc'theconneetionfminually: a In ,order tol signahtlie Operator, rthefcalled -jsiibscriber Willi operate; his; calling /dev'ice for the Idigitl ltheieby causing -the f, xauxiliary connectorswitohnto step. to t-he-'rst leeland then be a 'uto'matically releasedi f Byvtheseojperations the linedampassociated .with the trunkline in thekattendants-cabinet will be lighted and the, attendant operator: will .throw her listening key in .orderfto ascertain the numbei" ol :the1 siibsc'i'iber=tlesi1fed. :After; tinding- -out ithe numberff of the' desired {subscribers t line l'fthe,= opeia toi nvill insert the plug lJ associated with, the trunkl line-.into the j'ack 'ofA a: localsubstat'i'on. This line will then be automatically signalled." z i@ lVhen this last calledf subscriber answers he will be `in communication with the calling subscriber in the main exchange and the ther called subscriberin the privateautomatic exchange. The last called'party has alsocoutrol of the dual'connector H` in the same-manner as if'he werecalled through thef medium of' a dual switch.A Thus' by operating his calling v device `he may release vthe Vmain connector H or by hanging up his receiver d'isassociate his line completely from the incoming trunk line. also the other called subscriber in the branch exchange is enabled b v operating his callingv device to disassocialc the subscriber called by means of the plu;r from the connection.

Under certain conditions it is desirable that certain linesin the private automatic exchange may Vbe made inaccessible to the calling subscriber. In this case, when he attempts to, operate one of the dual connectors H or H into engagement with this barred line the operated connector switch will beautomatically released and a distinc-i. tive etone giventofthezcalling;subscriber in.

or'der towinorin .him thatghe isv unable Eto connect :with this, .line- However, i the'calL ing,r subscriber may connect.l Ewfith the ,non-J barrediiline'and requestj thejcalled; subscriber .toL ,place Ahim in connection with 'the barred, line. .-Thezcalled subscriber willbe able to do this as the barredline is not:

inaccessible to.- av private. automatic `exchange subscriber. n 1

' .,ufi'-.f'gfi "gwiiifg Instead of signalling one ottithe branch;

vice for the-digit y ,operate .the auxiliary connectorgswitch H- t o .the tenth level .whereupon it. would lne-automatically released.V y

tliese-'opcratioms fthe attendant; opei'artorqis 5v '.il l Y i v scriber. byA replacing. his receiver .upon the ,'llie attendant 4operat ini the private aittoniatic :exchange may" for certaini reasons desire 'to Iextend all lcalls: received over Axthe tiyii/nkilin'es tothe desiiedlfbraneh exchange. subscribleijgiln;order to Vdo this'she will restore one'lof lierkfeylsto normalf`Now when :L /sul?,scrilvierv in fthef exchange such as theo'iie/ at siilist'atioiif'A` `connects withl the trunk linefte'iniinating in 'thejdual switches H and Hi'he will vb eiinable to operate; the switchesand; a. line lampwvill appear before the operator; lShe. may complete the con'- nection, through automatically"'by wa)vv ot the du'al' switches lor manually by way of vnightv plug P2. If the call is extended automatically, when the called subscriber ansvveiswthe connection maybe transferred by thatsubscribcr in the usualinanncr `to '.inyof the branch exchange subscribers accessible to the duals-witcliesby way Aof the main" connector 'associated -witli lthc trunk line., i

d The dualfconnectors also have access yto trunk lines leading tofan visolated private branch exchange, this being shown immediately belovvandto the right of the dotted lines in 'the lower right hand corner of the sheet. AIf the calling subscriber had desired connection withv vthis private branch ex change the, attendant could have operated the main (lual connector H into engagement with the trunk line extending'fto this cxchange. By this operation the operator -in the'private branch exchange would be signalled and she will answer the call by insorting the plug of the cord circuit, such lUll llt)

as the oord circuit O', into the jack J and after ascertaining the number of the local subscriber` desired, extend the cull to that subscriber by way of the calling end of the cord circuit. j After the conversation is terminated both subscribers will replace their .receivers upon the switohhook. When thc visor-y signulin `the cord circuit O is operatedand local branch exchange operator is thereby. notified thattheconversation is ter- -Illinatedond She will withdraw the plugs of the cord circnitpO fron; the associated jacks. There arco number of special Connections lwhen the calling subscribers in the Ina-,in exchange are onlynllowed n limited use ot' the dual connector switches H and H.

When it is `1deeiredthat this class. of service should ho.g1ven,.the nttendnntoperatcr 1n the private automatic exchange will operate certain .keysnssociated with the incoming trunk lines. Thenperation when a calling subscriherinthe main exchange connects with one of these trunk lines nndeivthcse conditions will now be briefly described.

Again =it will be Aassumed that the calling lsubscriber is at substation' A. in the main 'exchan e and is connected to the trunk line associa ed with the switches H and H by way of theindividunl line switch C, selector D and-selector repeater E. When the celling device at the calling substation is operated lfor thenext two digits the main connector Il is operated .into engagement with the desired called subscrihers line which it will be .assumed is that ofthe substation A. If connection' is made therewith the calling.r subscriber is prevented from passing the call and has to release and in order to establish a new connection if another branch exchange subscriber is desired. provided of course the subscriber at substation A* does not answer.

Should one of the other keys at the -attendant operators position be thrown. the

. calling subscriber may control .thc dual switches until a branch exchange subscriber answers afterwhich the calling subscriberis prevented from passing the call. In both the above crises .either oi the called subscribers upon answeringr could transfer the call in the usual manner. In either case after the conversation is terminated the release will tnke place in the ordinary manner.

Under certain conditions the calling suhs-criber nur v find it desirable to signal the attendent operator in the branch exchange directly. In order to do this if the trunk line extending to the branch automatic ex- H and H.

'..endmoy pass the cell hyA this means.

Change is busy he will operate his calling device for a particular digit thereby causing the main dual Connector switch to step to a certain level and then release. These operations will sig-nal the attendant Operntor who will attend to his wants in the usual manner.

ln the above descriptions was Stated in a Ageneral way the ordina-ry connections from the main to the hranchexchange .when the attendant operator is on duty.A At night1 however. the attendant operator is not at her position and some provision must he made to handle calls coming into the private automatic exchange, In order to do this the. night'plug associated with the incom- .ing trunk .line isinserted into the jack of .the substation which is to he connected for night Service .and at which the watchman or some other employee is located during the time when the trunk is connected for night service. .For the purpose of description it will again he assumed that the calling subscriber at substation A has seized one of the trunk lines extending to the branch exchange and .terminating inv dual connectors 'When such a night connection iS up inmediately upon the trunk line beingseized the pre-connected local Substation is automatically signalled. Upon answering the subscriber at this telephone has complete control of the -rnain dual switch H It.

might have happened that the subscriber in .the main exchange desired a particular party in the branch exchange with which he desired toobtain connection during the nitl'ht- Immediately upon seizing the trunk vline the automatic ringing:l ot the pre-connected local line would begin but upon the first impulse in the next digit dialled by the calling subscriber the night plug P2 is completelv disassociated from the trunk line and the dual connectors niay be controlled by the culling subscriber in the ordinary manner.

lVhile the local substation is thus connected up for night service it may be celled by a local subscriber such us the one at substation A5 through the medium of theindividual linie switch C5, and a local branch exchange first selector such as D2, and a local connector' which has access to the line of the substation A5. The preconnected substation is also eble to call t-hrou h the medium of the individual line switc i. During the time when this substation is seized either for the reason that it is calling or being called the associated trunk line with which it. is connected for night service is busied in the main exchange.

When the main exchange is operating! manually all the connections above described may he set up and controlled hy a main exchange operator though in this case there 

